Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

155 lines (143 sloc) 4.835 kb
/* $Header: /cvsroot/osrs/libtiff/libtiff/tif_thunder.c,v 1.1.1.1 1999/07/27 21:50:27 mike Exp $ */
/*
* Copyright (c) 1988-1997 Sam Leffler
* Copyright (c) 1991-1997 Silicon Graphics, Inc.
*
* Permission to use, copy, modify, distribute, and sell this software and
* its documentation for any purpose is hereby granted without fee, provided
* that (i) the above copyright notices and this permission notice appear in
* all copies of the software and related documentation, and (ii) the names of
* Sam Leffler and Silicon Graphics may not be used in any advertising or
* publicity relating to the software without the specific, prior written
* permission of Sam Leffler and Silicon Graphics.
*
* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
*
* IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
* ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
* OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
* WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
* LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
* OF THIS SOFTWARE.
*/
#include "tiffiop.h"
#ifdef THUNDER_SUPPORT
/*
* TIFF Library.
*
* ThunderScan 4-bit Compression Algorithm Support
*/
/*
* ThunderScan uses an encoding scheme designed for
* 4-bit pixel values. Data is encoded in bytes, with
* each byte split into a 2-bit code word and a 6-bit
* data value. The encoding gives raw data, runs of
* pixels, or pixel values encoded as a delta from the
* previous pixel value. For the latter, either 2-bit
* or 3-bit delta values are used, with the deltas packed
* into a single byte.
*/
#define THUNDER_DATA 0x3f /* mask for 6-bit data */
#define THUNDER_CODE 0xc0 /* mask for 2-bit code word */
/* code values */
#define THUNDER_RUN 0x00 /* run of pixels w/ encoded count */
#define THUNDER_2BITDELTAS 0x40 /* 3 pixels w/ encoded 2-bit deltas */
#define DELTA2_SKIP 2 /* skip code for 2-bit deltas */
#define THUNDER_3BITDELTAS 0x80 /* 2 pixels w/ encoded 3-bit deltas */
#define DELTA3_SKIP 4 /* skip code for 3-bit deltas */
#define THUNDER_RAW 0xc0 /* raw data encoded */
static const int twobitdeltas[4] = { 0, 1, 0, -1 };
static const int threebitdeltas[8] = { 0, 1, 2, 3, 0, -3, -2, -1 };
#define SETPIXEL(op, v) { \
lastpixel = (v) & 0xf; \
if (npixels++ & 1) \
*op++ |= lastpixel; \
else \
op[0] = lastpixel << 4; \
}
static int
ThunderDecode(TIFF* tif, tidata_t op, tsize_t maxpixels)
{
register u_char *bp;
register tsize_t cc;
u_int lastpixel;
tsize_t npixels;
bp = (u_char *)tif->tif_rawcp;
cc = tif->tif_rawcc;
lastpixel = 0;
npixels = 0;
while (cc > 0 && npixels < maxpixels) {
int n, delta;
n = *bp++, cc--;
switch (n & THUNDER_CODE) {
case THUNDER_RUN: /* pixel run */
/*
* Replicate the last pixel n times,
* where n is the lower-order 6 bits.
*/
if (npixels & 1) {
op[0] |= lastpixel;
lastpixel = *op++; npixels++; n--;
} else
lastpixel |= lastpixel << 4;
npixels += n;
for (; n > 0; n -= 2)
*op++ = lastpixel;
if (n == -1)
*--op &= 0xf0;
lastpixel &= 0xf;
break;
case THUNDER_2BITDELTAS: /* 2-bit deltas */
if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP)
SETPIXEL(op, lastpixel + twobitdeltas[delta]);
if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
SETPIXEL(op, lastpixel + twobitdeltas[delta]);
if ((delta = (n & 3)) != DELTA2_SKIP)
SETPIXEL(op, lastpixel + twobitdeltas[delta]);
break;
case THUNDER_3BITDELTAS: /* 3-bit deltas */
if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP)
SETPIXEL(op, lastpixel + threebitdeltas[delta]);
if ((delta = (n & 7)) != DELTA3_SKIP)
SETPIXEL(op, lastpixel + threebitdeltas[delta]);
break;
case THUNDER_RAW: /* raw data */
SETPIXEL(op, n);
break;
}
}
tif->tif_rawcp = (tidata_t) bp;
tif->tif_rawcc = cc;
if (npixels != maxpixels) {
TIFFError(tif->tif_name,
"ThunderDecode: %s data at scanline %ld (%lu != %lu)",
npixels < maxpixels ? "Not enough" : "Too much",
(long) tif->tif_row, (long) npixels, (long) maxpixels);
return (0);
}
return (1);
}
static int
ThunderDecodeRow(TIFF* tif, tidata_t buf, tsize_t occ, tsample_t s)
{
tidata_t row = buf;
(void) s;
while ((long)occ > 0) {
if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth))
return (0);
occ -= tif->tif_scanlinesize;
row += tif->tif_scanlinesize;
}
return (1);
}
int
TIFFInitThunderScan(TIFF* tif, int scheme)
{
(void) scheme;
tif->tif_decoderow = ThunderDecodeRow;
tif->tif_decodestrip = ThunderDecodeRow;
return (1);
}
#endif /* THUNDER_SUPPORT */
Jump to Line
Something went wrong with that request. Please try again.